Process and mechanism for separating intermixed divided materials



Nov. 4, 1941. R. PEALE ETAL PROCESS AND MECHANISM :FOR SEPARATING INTERMIXED DIVIDED MATERIALS Filed Aug. 9, 1939 6 Sheets-Sheet l 3 zE 2953 E fNV NTOR 1 MMW ATTORNEYS Npv. 4, 1941. R. PEALE ET AL 2,261,278 PROCESS AND MECHANISM FOR SEPARATING INTERMIXED DIVIDED MATERIALS Filed Aug. 9, 1939 s Sheets-Sheet 2 MENTOR r ATTORSSYS Nov. 4, 1941. R. PEALE ETAL 2,261,278

PROCESS AND MECHANISM FOR SEPARATING INTERMIXED DIVIDED MATERIALS Filed Aug. 9, 1959; GSheets-Shet 5 w v. a 2 Q Q r & I

MIXED DIVIDEDMATERIALS Nova 4, 1941;

R. PEALE ET AL PROCESS AND MECHANISM FOR sEPA RATING INTER Filed .Aug. 9, 1959 6 Sheets-Sheet 4 sucnon AN'oRNEYs Nov. 4, 1941.; R- 'PEALE Em 2,261,278

PROCESS ANDMECHANISM FOR SE IPARATING INTERMIXED DIVIDED MAT EBI ALS Filed Aug. 9, 1939 6 Sheets-Sheet 5 Nov. 4, 1941. R. PEALE ETAL 2,261,278

PROCESS AND MECHANISM FOR SEPARATING INTERMIXED DIYIDED MATERIALS Filed Aug. 9, 1939 6 Sheets-Sheet 6 FAN wig 12.

I I l l l Patented Nov. 4, 1941 PROCESS AND MECHANISM FOR. SEPABAT- V ING INTERMIXED DIVIDED MATERIALS Richard Peale and Rembrandt Clearfleld, Pa.

Beale, .ha,

Application August 9, 1939, Serial No. 289,134

14 Claims.

The invention relates to processes and mechanism for separating intermixed divided materials according to their specific gravities, such as coal and its impurities, and more especially to such processes and mechanism employing air as the stratifying agent. 5

Objectsand advantages of the invention will be set'forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and combinations pointed out in the appended claims.

The invention consists in the novel parts, 'con-' structions, arrangements, combinations and ,im-

provements herein shown and described. I,

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention. 4

Of the drawings:

' and attained by means of the instrumentalities Fig. 1' is a top plan, with parts broken away,

of a separating table embodying the invention;

Fig. 2 is a longitudinal side elevation of the table shown in Fig. 1;

Fig; 3 is a Fig. 1;

Fig. 4 is an enlarged vertical section on line 4-4 of Fig. 1;

Fig. 5 is a diagrammatic plan View of the saparator deck, indicating the surface slopes;

vertical section on line 3-3 of while in other respects the invention comprises independent novel subject matter.

The invention is directed to providing an improved pneumatic-stratification separating'process, and a mechanism therefor, in which the stratifying air currents are guided and directed through the bed of intermixed materials so as to avoid size classification or segregation of the particles during the separating. action. More particularly, and especially as applied to the purification of coal containing fines, theinvention' controls the direction and force of the air currents passing through the bed so that the finer particles are not displaced upwardly nor blown toward or out-,of the top of the bed. By means of the invention the distribution of sizes within the bed of coal is maintained as homogeneous as possible, thereby contributing to uniformity of 1. air pressure and maintenance of the desiredstatic pressure and conditions throughout the bed.

The present invention. by preventing vertical stratifying escape of air currents through the top of the bed, i prevents the above-described displacement and segregationof the fines, thus keeping the bed in a uniform size condition conducive to stratificaq I tion. The invention .providesa method and a means for insuring that the air currents will.

- travel intoand through the bad very largely in Fig.6 is a vertical section on line' B'B of Fig; 1;

Fig. 6 -A is an enlarged fragmentary detail of a modification of the air duct construction shown in Fig. 6;

Fig. 7 is a vertical section on line 1-1 of Fig. 1;

Fig. 8 is a vertical section on line 8--8 of Fig. l;

-Fig. 9 is a vertical section on line 9-9 of Fig. 3;

Fig. 10 is a partly diagrammatic horizontal secticn, showing the construction and arrangement of suction ducts below the separatordeck;

' Fig. 11 is a longitudinal sectionon line ll- -ll 0: Fig. 10; and V Fig. 12 is a reduced side elevation of a separating table showing a modified form of suction supply. 'i'he present invention is-in many respects an improvement over the process and mechanism disclosed and claimed in our copending applicahorizontal or transverse non-verticak paths.

Consequently, theair actionmay be made fairly energetic and a considerable pressure drop and loosening effect be provided by the air currents without, attendance of the undesirable blowing of the fine material up and out of the bed. As the fine refuse is prevented from rising to the surface of the bed, it will readily settle and remain settled with the other sizes of refuse in the lower strata. In forms of.the process and mechanism utilizing transverse fiowage of the settled refuse and flotant coal strata, the invention also prevents the fine refuse material from being blown or carried over the tops of the rililes or separating partitions on the deck. Further, by causing the air currents to travel largely in the horizontal direction within the depth of the bed, there will be very little dead air space in the bed, regardless of the existence of imperv'ious'portions in the deck surface. Preferably the cross currents or horizontal drafts of air are fairly closely controlled locally so as to maintain the desired directio'nal efiect without undue air force or velocity. It is desirable to avoid a sweeping of air I blasts over or through the bed surface, which tion ,Serial No. 232,808 filed October 1, 1938; 55 might tend to displace strata laterally.

permitting the use of relatively small air with: drawal ducts of uniform cross section and providing for the maximum air action desired at all points within the bed. The invention further provides superior means for regulating the distribution and the velocity of air currents passing through the bed so as to insure the maximum efficiency of stratification while preventing esape of air currents vertically upwardly through the bed and/or otherwise acting to cause size segregation and dislodgement of the finer particles from a fairly uniform distribution throughout the bed. In this connection the invention provides a novel method and means for introducing air into the bed at levels above the bottom of the bed, whereby air passage through the bed may take place along such upper levels without rising from the bottom of the bed.

Another object of the invention is to provide means for removing settled finer particles of refuse or heavy material from the bed and from the separating deck relatively early in the'stratifying action. This feature of the invention permits continuation of the separating action on the remaining materials of the bed without disturbing stratification and permits application of more vigorous separating action or supplemental treatment of a different sort to the remaining materials from which fine refuse has been removed. Moreover the novel method and means of removing fine settled refuse early in the process makes it possible to apply a relatively short separating action to beds of 'materials.wherein the -tangular outline having a feed end 2 and a discharge end 3. The deck I is supported in a boxlike frame III which reciprocates with the deck. The deck as shown is preferably longitudinally reciprocablc, the frame III being mounted for that purpose on inclined links I, the upper ends of which are pivoted to the deck and the lower ends pivotally supported from stationary abutments 6. The driving means are not shown and range of sizes is in the relatively fine or slack v sizes and/or where the refuse is predominately in the finer sizes. Those features of the ,invention which obviate the size displacement and suspension of the finer particles are conducive to early and rapid settling out of much of the fine refuse and thus make possible the relatively early .separate'removal of such fine refuse.

It will be understood that the invention is generally applicable to the separation of, intermixed divided materials varying in specific gravity, but is particularly directed to the purification of unsized raw coal, or coal containing fines," the principles of separating action in accordance with differences in specific gravity and in spite of variations in size being utilized in accordance wth the general practice of the Peale-Davis process. Many features of the invention are particularlv applicable to the treatment of the finer .to those shown and described in our said it will be understood that the mounting and the reciprocating mechanism for the deck are not essential features of the invention, the process being generally applicable to pneumatic separating tables whether stationary or moving, will be clear to those skilled in the art. An air-tight cover II overlies the entire deck surface and is fast to the end and side walls of the frame I0 so that the entire upper surface of the deck is closed from access to the atmosphere. A feed trough I2 at the rear end of the deck is flexibly connected to a coal feed hopper I3 having a vaned rotary feeder I4 which acts as a valve to feed coal into the chute I2 but to prevent any substantial amount of air from reaching the space above the deck. In general it will be clear that the foregoing features of the cleaning table are similar copending application Ser. No. 232,808.

In accordance with the invention means are provided for applying suction to the space in levels lying a limited distance above the surface of the deck I so as to draw air currents upwardly through the deck and transversely through the bed of materials and out ofthe bed without permitting passage of such air currents upwardly to escape through the top of the bed. Atmospheric air is admitted to the bottom of the bed of materials through the air pervious deck and to a limited extent at levels within the bed and above the deck so as to provide a thorough aeration of the materials of the bed but without forcing air currents out of the bed through the top. Said air supply means are further adapted to act as separating guides and partitions for the materials during stratification thereof so as to prevent cross As embodied the side walls I5 and I6 of the frame Ill extend downwardly from the top II to provide a. suction or low-pressure housing or chamber of rectangular cross section beneath the deck and entirely surrounding the same (Fig. 6). To maintain uniform low pressure conditions throughout said chamber, the bottom wall or plate II of said chamber is preferably sloped forwardly and upwardly to terminate at the front end wall I8, while the rear end of said chamber extends rearwardly at I9 to communicate with a suction fan, not shown. The deck I is suspended within the upper part of the main suction chamber and is housed within a secondary atmosphere or high-pressure chamber having side walls 2|] and 2| and bottom plates 22 which extend longitudinally of themain chamber on an angle substantially midway between horizontal and that of the sloping bottom IT. The walls 20 and 2| terminate a substantial distance above the top of the deck I and are supportingly connected thereto by longitudinal girders 25. The tops of girders 25 are connected to inner deck suspending walls 28 which extend upwardly a' short distance above the top edges of walls 20 and 2| and thence are inclined upwardly and outwardly to be connected to and supported by the side walls l5 and I6. As indicated in the drawings the space within the secondary or pressure chamber formed by the deck'l, the side walls and 2! and the bottom plates 22 is open to the atmosphere at the rear end of the table, through the orifice 28. The size of the orifice and volume of the chamber are such as to maintain air therein substantially static at atmospheric pressure.

It will be clear from the foregoing that suction conduits A and B are formed between the mainsuction chamber and the side walls 20 and 2| of the secondary pressure chamber, whereby air may be drawn upwardly through the deck i and through the bed of material (the top of which is indicated by the broken line T). Communication between the sides of the bed and the suction ducts 'A and B is afiorded by perforations 30 in the vertical walls 26. It will be noted that these perforations extend upwardly from near the top of the deck to a level just below the top of the bed '1 so that air may be drawn up through the deck and transversely to the side of thebed through out the entir depth of the bed. The intensity and relative amounts of air which are directed to pass through various levels within the bed may be controlled by the extent and distribution of tions 30m in the baflle walls 20 and 2! between the tops of the girders 25 and the top of the baiiie walls. It will be clear that by varying the amount and/or distribution of perforations a, practically any desired distribution and direction of air currents between the pervious deck i and the sides of the bed may he obtained.

As embodied; supplementary means are preferably provided for introducing atmospheric air into the bed at levels above that of the deck i, such means also acting as material-guiding and separating partitions. As embodied, a plurality of hollow casings or conduits C are mounted on the surface of the deck i to-extend longitudinally,

' therealong at spaced parallel sections.' Said casings C are formed with vertical walls which extend above the top of the bed T and are roofed over with inverted v-shaped surfaces 36". The

vertical walls 35 are preferably supported on iongitudinal, spacedeapart girders 3.1 which extend from slightly above th top of the deck for a substantial distance downwardly into the secondary atmosphere chamben.

The space between the girders 31 thus provides [a relatively long and narrow inlet for atmospheric air from the pressure'chamber to the casing C. Perforations 38 are provided in both vertical walls 35 of the casing whereby atmospheric air may be drawn from within the casing C into the upper levels of the bed and thence across the bed to exit through the side wallperforations 30, as indicated by the arrows, Fig. 6. Preferably the upper level of the perforations 35 is spaced somewhat below the top of the bed ,T and lower than that of the upper level of perforations 30, thereby causing the air currents from the casing C to have a slightly. upward directions across the bed but without escaping from the top thereof. The perviosity of the suction walls 26, of the pressure walls 38- and of the deck I may all be zoned or varied throughout the length of the bed as desired so as to provide the most effective air action for any particular coal.

In practice the bed of materials is preferably divided longitudinally by a plurality of the airpressure partitions or casings C so as to subdivide the bed intoa number of relatively long and narrow sub-sections, whereby the direction and intensity of the air currents can be emciently andnicely regulated. As shown, the separating table is] provided with two such parallel casings C spaced from the side walls 28 about one-fourth the width of the deck i With such arrangement there, is also provided an intermediate air-suction or low-pressure casing D along the central line of the deck,'thereby to provide a source of air suction within toe bed and arranged symmetrically with rcspe'ct to the inner walls of the twoair-pressure casings C. As shown, the suction casing D is shaped and constructedexteriorly in aform substantially identical with that of the casings C, having vertical walls 40 with perforations lltherein and a similarly shaped top closure 42. The lower edges of the walls at are supported upon longitudinal, downwardly extending girders 63 similar to the girders 3?. However, the'interior of the suction casing D is designed to communicate with the main suction chamber below the deck and tobe excluded from communication with thb atmosphere. For this purpose longitudinal inner walls extend downwardly from near the top of casing D to communicate with the main suction chamber, thereby effectively dividing in two the secondary pressure or atmosphere chamber below the deck. There is thus-formed a suction or low pressure conduit E running from the interior of casing D to the main suction chamber below. As will be clear from Fig, 6, atmospheric ai is drawn into casing D through the perforations ti, such air coming both from the intermediate sections of the deck i and from the adjacent-walls 35 of the casings C. Thereby the various sub-divisions or longitudinal sections of the bed are traversed by air currents of the desired direction and distribution in a substantially uniform manner. It will beunderstoo'd that the number or pressure casings Gland suction conduits A, B and D are not'limited' to those here shown but may bearranged and distributed as desired in accordance with the, size of the mechanism, the material to be treated and the amount of aeration required. Ordinarily; however, a symmetrical arrangement providing alternating sources of high and low pressure, as shown, is the preferred form of the invention.

Referring now to the general arrangement of the separating table and the travel of the materials thereon, the bed of .coal is formed at the rear end below the feed chute l2 and, through the impulsion of the reciprocating movement of the table, travels generally forwardly along the deck in a plurality of sub-beds l'ongitudinallypdi-. vided by the casings C and D. In accordance.

with Peale-Davis practice the depth of the bed is substantial and is preferably maintained at a uniformheight as indicated by the broken line T. Beginning at the feed end the separating deck is rectangular for a substantial part of its length and the direction of travel of all the materials thereon is straight forward in the direction of reciprocation. As appears in Figs. 1 and 5, this rear rectangular portion R of the deck is transversely horizontal, and in that portion the casings C and D are parallel to the longitudinal axis of the table and their height is such that their tops extend a substantial distance above the level T of the top of the bed.

Beyond a median transverse line 50, the deck is preferably widened toward the inner or refuse side, the side wall 5| being inclined forwardly and away from the center of the deck and thence again straight forwardly so that the front portion of the table beyond the line 50 is substantially wider than the rear portion R. As indicated in Fig. 5 this front portion of the deck is provided with differently inclined portions as follows: The triangular section S just beyond the median line 5|] inclines longitudinally downwardly to the borderline 52. Thereafter, the triangular area U is inclined laterally downwardly at a. gentle angle from the borderline 53 toward the opposite side of the deck. The refuse zone or area V along the wall 5| in front of the borderline 50 continues horizontal at the level of the rear section R. Beyond the diagonal borderline 54 (marking the terminus of the perforated portion of the deck) there is provided a forwardly and downwardly inclined section W which comprises, an impervious plate 55 which acts as a coal discharge chute. An orifice 56 is provided in the end wall 3 of the main casing ill for permitting the discharge of material from the end of chute 55 and from the horizontal refuse zone V. A vertically adjustable coal discharge gate 51 is variably positionable vertically with respect to the orifice 56 and controls the exit of coal from the casing and plate 55 onto a delivery chute 58. Similarly a vertically positionable gate 59 is provided for handling the discharge of middlings from the casing onto a middling chute 60, while a separate vertically positionable gate 6| controls the discharge of refuse from the zone V into the discharge chute 62. The relative quantities of coal and middlings delivered from the plate 55 may be regulated by the rotatable vane 63 between the gates 51 and 59.

In accordance with the invention the materials undergo a-preliminary stratification action in the rear longitudinal stratifying area R and in that area a certain amount of settled fine refuse may be removed from the bed as hereinafter described. Beyond the median line 50, the separating action is supplemented by inducing a transverse relative flowage of the flotant coal stratum and the settled refuse, the flotant coal travelling forwardly and somewhat laterally over the tops of separating partitions, while the settled refuse is guided by said partitions to'the refuse concentrating zone V along the upper or inner side of the deck and thence to discharge at the front end. In effecting this supplemental transverse separating flowage of the materials, the depth of the bed is preferably somewhat diminished by spreading out the materials over the wider forward portion of the deck, while at the same time the non-vertical air action hereinbefore described is maintain'ed upon the transversely flowing and separating materials of the bed.

For this purpose the air distributing casings C and D in the more forward zones or areas S and U are caused to diminish in height so that they lie below the upper levels or strata of the bed in these areas and thereby function as separating partitions between the upper and lower strata of the bed. At the same time the casing; C and D are inclined from the straight forward direction they had in the rear zone R and are caused to extend forwardly and inwardly toward the wall 5| of the table. As will be clear from Figs. 1 and 3, these casings begin to diminish in height at points 10 slightly to the rear of the-median line 50 and taper down from their maximum height to a minimum which is well below the top of the bed and preferably less than an inch above the deck. This minimum height is attained approximately along the border line 52. Also beginning approximately alongsaid border line 52, the casings C and D incline forwardly and toward the inner wall 5|, as shown. Thus the zone or area S outlines substantially the space within which the transition in shape, height and direction of the casings C and D is accomplished. From said line 52 these casings extend forwardly and inwardly, but terminate substantially along the border line 53 to provide an unobstructed refuse concentrating zone V. It will be noted in Figs. 1, 3 and 4 that the V-shaped outline of the tops of the casings C and D preferablyterminat'es at the point 10, the tops II of these casings thereafter being flat in cross section.

An additional aerating and material-separating partition F is provided along the terminal diagonal edge 5| of the deck. As embodied, the air suction conduit B is extended diagonally from the outer wall 15 of the deck parallel to the inclined portions of the casings C and D and terminates parallel with their ends at the end wall 3 of the main frame l0. The casing F is constructed in shape and arrangement generally similar to that of the forward inclined portions H of the suction casing D, having the flat top 12 r and a perforated rear vertical wall 13. However,

the forward wall ll-of casing F is preferably inclined forwardly and downwardly to merge withthe plate 55, thereby to facilitate discharge flowage of coal onto the plate. Wall 14 is also imperforate, no air being drawn into casing F from the forward side.

As willbe clear from Figs. 4 and 10, suction communication between the main suction chamber and easing F is established by vertical conduit walls 8|! and 8| which extend upwardly from the suction chamber to the casing and constitute in effect a. transverse continuation of the suction chamber walls I6 and 2| forming the conduit B.

Referring now to those features of the invention which provide for preliminary elimination of settled fine refuse during the early course of stratification, said special refuse removal means are shown in Figs. 1, 2, 3, 8 and 9. In accordance with this feature of the invention, fine settled refuse travelling along the bottom of the deck near the forward portion of the rear zone R is removed directly from the bottom of the deck without interfering with the continued forward travel of the remaining materials of the bed. Particular provision is made for assuring that only the fine heavier materials will be removed by this means while the fine coal particles will remain intermixed in thebed with the coarser coal. The coarser pieces of settled refuse will also continue forwardly for transverse separation and disposal to discharge from the refuse concentrating area V.

As embodied, a transverse slot or opening is provided to extend entirely across the deck I near the forward end of the rear zone R. Spaced from the rear edge '99 of said slot and below the level of the deck is a rotatable shaft 9| having a sleeve 92 fixed to rotate therewith. A space 93 is lighter particles are guided forwardly and into ja providedbetween the edge 99 of the-slot and the solid core 92 of the sleeve whereby refuse settled on the pervlous deck I mayjdrop over'the edge I 99 and between said edge and the core 92 ofthe' sleeve. The forward edge 94 of the refuse slot is placed as closely as possible to the surface of the rotatable core 92 and is bevelled to permit a close moving fit. Thus ,refuse travelling forwardly along the. deck may drop into the opening 93,

middlings receptacle I9Iby an adjustablej'dfim'. 7

ing blade I06.

Regulation of the amount of middling and/or vane I 91. Vanes I93 and-I9! are tionable by means of handles 1 I9 and I II respecexternal handle H2. The

while material passing over the core 92 will be carried onto the deck over the lip 99. The sleeve 92 and shaft 9| are rotated in the direction of the arrow (Fig. 3). to so advance materials which do not fall into the slot 93. Means for so rotating the shaft 9| comprise a motor 95' mounted on the outside of the frame l9 and driving the shaft through suitable gearing 96 and variable speed reduction 91. Thus fine refuse material which has settled to the surface of the deck I will,tend

tively while blade ms is'similarly adjusted by 7 materials held in the discharge receptacles IM and I95 are discharged toward opposite sides of these receptacles being inclined downwardly and outwardly in opposite directions to discharge chutes or spouts II3 on the ends of these spouts may be provided to prevent substantial leakage of air into the receptacles.

I or the refuse to be removed is all in fine sizes.

.to fall into the opening 93, while any material at even slightly higher levels will tend to cross the gap 93 and be carried forwardly by the rotating core '92 and continue along the deck. Similarly any material too coarse to fall into the opening 99 will be urged away therefrom by the rotating core. .The core also tends to cause material to pile up behind it to a slight extent before going on. This tendency insures that the settled refuse will accumulate and fall into the slot while lighter material will move on.

Means are provided for preventing large chunks of material from falling into or becoming wedged in the opening 93. As shown, a plurality of closely spaced circular vanes 95 extend from the periphery of the solid core 92 of the refuse roller to just short of the lip 99 of the opening. Thusthin wide pieces of material cannot slide into'the opening but will be carried over the opening and away therefrom. The forward edge 99: of the 'opening is serrated to provide notches through which the vanes 95 ,can rotate. The si'ze of the fine refuse'permitted to enter the gap can be controlled between the vanes 95, a i

Means are provided for disposing of the fine limited to the specific 49. by varyingithe spacing v refuse delivered. into the opening 93 and, co-- operating thierewith, means for preventing lighter material of small size .from falling into said opening or from thereafter being discharged with such separated heavy fines.' As embodied, a curved plate I99 leads from the rear edge 99 of the slot. around the roller 92 and then forwardly into a refuse discharge receptacle I 9!.

The plate I99 is. perforated at I92 to cause air to be drawn upwardly therethrough from the atmosphere chamber and back through the slot 99. Thus a supplementary air blast issues upwardly through opening 93 and tends to prevent fine coal particles from falling with the .refuse into theI't'rap. An adjustable vane I99 is provided at the mouth of the receptacle I9I so as to regulate the admission .of refuse into the receptacle, thereby building up .a body, of fine material flabove the plate I92 and subjecting that material to control and. additional stratification, The body of material so held in the receptacle I9I will act to prevent any but the lowermost settled particles from settling into the gap 99 so that fine coal will'move along onto the rollers. Any

; lighter material inthat body will be floated and tend to stay above the bottom stratum which Thus the invention coal-free refuse will be H delivered from receptacle When the coal to be treated is quite fine,

the table and the treatment therefrom may be curtailed to the rear straight portion R and the forward, transverse-flowage sections S, U and V may be dispensed with.

The modification shown in Fig. 12 provides a table having a plurality of suction fan outlets whereby several suction fans may be used to increase and maintain uniform the desired lowpressure conditions beneath the deck. As shown there 18 provided a'fan outlet for a fan at either end and the chamber below the deck is shapedaccordingly; however, several more fans may be the chamber at intervals along the tapped into table where greater tion is required.

The invention in its broader aspects is not mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principlesof the invention and without sacrificing its chief advantages.

What we claim is:

.suction or uniformity of suc- 1. .45. pneumatic-stratification mechanism for separating intermixed divided materials varying" in specific gravities including in combination from a level between the top and bottom thereof 4 and out of the bed between said levels and means Y for separately delivering the flotant 'stratum of I flows over the edge of vane I93. These upper. 79

lighter. material and the settled heavy material.

3. A pneumatic-stratification mechanism for separting intermixed divided materials varying in specific gravities including in combination means for maintaining a bed of saidzmaterials of substantial depth undergoing progressive,

stratification while traveling along a support.

7 lightermaterial admitted to the receptacle I may be effected by an adjustable externally posiof thetable, the bottoms and Ill respectively, If necessary means such as one-way covers or flaps Provides that omy fine,

bed of said materials undergoing progressive,

means for drawing air currents through the bed from a level between the top and bottom thereof and out of the bed between said levels, means for also drawing air currents upwardly from the bottom of the bed and out of the bed between said levels and means for separately delivering the flotant stratum of lighter material and the settled heavy material.

4. In a pneumatic-stratification separating mechanism, in combination, means for maintaining a bed of materials undergoing stratification on a support, means along one side of the bed for supplying air of a relatively high pressure, means along the opposite side of the bed for maintaining air at a relatively low pressure, the bed forming an air-current path between said means and means for confining the passage of air between the top and bottom levels of the bed.

5. The process of separating intermixed divided materials which comprises maintaining abed of said materials of substantial depth traveling along a support and undergoing specific-gravity stratification, introducing air currents into the bed at levels between the top and the bottom of the bed, passing said air currents through the bed between said levels andremoving them from the bed between said levels and separately delivering the fiotant stratum of lighter material and the settled heavy material.

6. The process of separating intermixed .di-

vided materials which comprises maintaining a l said support for the entrapment of fine settled heavy material, a rotating member mounted be- .yond said gap to impart a supplementary advancing movement to other materials in the bed in the direction of travel of the bed to prevent same from being trapped in the gap, said member having spaced sizing members extending across the gap to prevent entrance of coarse materials into the gap, said support being air pervious and means for passing air currents through the support and bed of material thereon to effect a said stratification, and means at said gap for bed of said materials of substantial depth traveling along a support and undergoing specificgravity stratification, introducing air currents into the bed at levels between the top and the bottom of the bed, passing said air currents through the bed between said levels and removing them from the bed between said levels, passing additional air currents upwardly from the bottom of the bed and separately delivering the i'lotant stratum of lighter material and the settled heavy material.

7. A pneumatic-stratification mechanism for separating intermixed divided materials varying in specific gravities including in combination means for maintaining a bed of said materials of substantial depth undergoing progressive stratification while traveling along a support, airpervious means exposed to atmospheric pressure throughout the length of the bed, air-pervious 3 means extending along the bed adjacent to said first air-pervious means and exposed throughout its length to a source of substantially constant suction or low pressure and means for passing air currents through said first means, through passing a supplementary current of air upwardly and rearwardly through the gap to prevent fine light material from being trapped therein.

10. In a pneumatic stratification mechanism in combination means for maintaining a bed of intermixed divided materials of different specific gravities undergoing progressive stratification while traveling along a support, means for passing air currents across the bed at levels between the top and bottom thereof for aerating and stratifying the particles, said means extending substantially throughout the depth of the bed at the part of the support adjacent the feed-on locus, and extending throughout only a part of the depth of the bed adjacent the discharge locus, whereby substantially all strata are aerated during the early stages of stratification and only a part of said strata during the later stages.

11. In a pneumatic stratification mechanism 'in combination means for maintaining a bed of intermixed divided materials of different specific the bed and into the second means at levels below the top of the bed.

8. A pneumatic-stratification mechanism for separating intermixed divided materials varying in specific gravities including in combination gravities undergoing progressive stratification while traveling along a support, means for passing air currents across the bed at levels between the top and bottom thereof for aeratingand stratifying the particles, means for discharging a iiotant superior stratum of coal and a settled stratum of heavy material from different parts of 'the bed and means for confining the passage of I said air currents to progressively lower strata of the bed as material from said fiotant stratum is discharged.

12. The process of separating intermixed divided materials which comprises maintaining a bed of said materials of substantial depth traveling along a support and undergoing specificgravity stratification', passing air through. the bed between the top and bottom levels thereof, said air currents being supplied to substantially all levels of the bed during the initial stages of stratification, but confining the means for maintaining a bed'of said materials of substantial depth undergoing progressive Stratification while traveling along a support, a gap in said support for the entrapment of fine settled heavy material, and a rotating member -mounted beyond said gap to impart a supple mentary advancing'movement to other materials in the bed in the direction of travel of the bed to prevent same from being trapped in the gap. the member having rearwardly extending spaced fins for preventing any coarse material from entering said gap, said support being air pervious and means for passing air currents throughthe support and bed of material thereon toefl'ect said stratification.

supply thereof to the lower levels of the bed during later stages of the separating action.

13. Theprocess of separating intermixed divided materials which comprises maintaining a 'bed of said materials of substantial depth travelcurrents of the strata of the bed to said air currents durdischarge, guiding a settled stratum of heavy maing the later stages of separating action. terial to discharge in a different direction, suba 14. The process of separating intermixed dijecting substantially the entire bed to the action vided materials which comprises maintaining a of said air currents during the initial stages of 'bed of said materials of substantial depth travelstratification, and subjecting only' the lower ing along a support and undergoing speciflcstrata of the bed to said air currents during th gravity stratification, passing air currents sublater stages of separating action; stantially horizontally through the bed between the top and bottom levels thereof, progressing a a RICHARD PEALE. fiotant superior stratum of lighter material to RENSRANDT- PEALE, JR. 

